JP2020024872A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of preventing an electrode of an outermost layer of a stack from being damaged.SOLUTION: A power storage device 1 comprises: a stack 2 formed by stacking a negative electrode 4, a positive electrode 5, a negative-electrode collection plate 6, and a positive-electrode collection plate 7; a laminate film 3 covering the stack 2; and a negative-electrode tab 9 and a positive-electrode tab 10 electrically connected to the negative-electrode collection plate 6 and the positive-electrode collection plate 7 and led out of the laminate film 3. The laminate film 3 has an upper exterior part 11 and a lower exterior part 12 arranged to face each other in a stacking direction of the stack 2, and the upper exterior part 11 and the lower exterior part 12 have substantially U-shaped cross sections, and have dummy layers 23 arranged between inner wall faces 13a, 16a perpendicular to the stacking direction of the upper exterior part 11 and the lower exterior part 12 and an upper end face 2a and a lower end face 2b in the stacking direction of the stack 2, outer shape dimensions of the dummy layers 23 viewed from the stacking direction being larger than outer shape dimensions of the negative electrode 4 and the positive electrode 5 viewed from the stacking direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage device.

  As a conventional power storage device, for example, a technology described in Patent Literature 1 is known. The power storage device described in Patent Literature 1 has a power generating element having a plurality of combinations of a positive electrode layer and a negative electrode layer, a polymer metal composite film covering the power generating element, and is taken out from the inside of the polymer metal composite film to the outside. And a tab.

JP 2006-128038 A

  However, in the above-mentioned conventional technology, since the polymer-metal composite film has a substantially U-shaped cross section, the edge of the outermost layer electrode in the power generation element (laminated body) is susceptible to external stress, so May be damaged.

  An object of the present invention is to provide a power storage device capable of preventing damage to an outermost layer electrode in a laminate.

  The power storage device according to one embodiment of the present invention is a stack in which an electrode and a current collector are stacked, an exterior member that covers the stack, and an electrical connection with the current collector, which is taken out of the exterior member. A tab, and the exterior member has a first exterior portion and a second exterior portion arranged to face each other in the stacking direction of the laminate, and at least one of the first exterior portion and the second exterior portion includes: A dummy layer is disposed between the inner wall surface perpendicular to the laminating direction and the end surface in the laminating direction of the laminate in at least one of the first exterior part and the second exterior part, having a substantially U-shaped cross section, The outer dimensions of the dummy layer viewed from the laminating direction are larger than the outer dimensions of the electrodes viewed from the laminating direction.

  In such a power storage device, the inner wall surface perpendicular to the laminating direction and the end surface in the laminating direction of the laminated body in the laminar direction of the laminar portion having a substantially U-shaped cross section among the first laminating portion and the second laminating portion constituting the laminating member. A dummy layer is disposed between the layers, and the outer dimensions of the dummy layer as viewed in the stacking direction are larger than the outer dimensions of the electrodes as viewed in the stacking direction. Therefore, when an external stress is applied to the power storage device, the external stress is applied to the dummy layer, so that the edge of the electrode of the outermost layer in the stacked body is less likely to receive the external stress. This prevents the outermost layer electrode in the laminate from being damaged.

  Each of the first exterior part and the second exterior part has a substantially U-shaped cross section, and the dummy layer has inner wall surfaces perpendicular to the lamination direction of the first exterior part and the second exterior part and both ends in the stacking direction of the stacked body. It may be arranged between the respective surfaces. In this case, since the edges of the outermost layer electrodes on both sides in the stacking direction of the laminate are less likely to receive external stress, damage to the outermost layer electrodes on both sides in the stacking direction of the laminate is prevented.

  A chamfer may be provided at an edge of the main surface of the dummy layer on the exterior member side. In this case, when an external stress is applied to the power storage device, the edge of the dummy layer is less likely to bend inward in the stacking direction, and a crack is less likely to be generated in the bent portion of the exterior member.

  The thickness of the dummy layer may be larger than the thickness of the exterior member. In this case, the dummy layer can sufficiently receive external stress.

  ADVANTAGE OF THE INVENTION According to this invention, damage of the electrode of the outermost layer in a laminated body can be prevented.

1 is a plan view illustrating a power storage device according to one embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II of FIG. 1. FIG. 2 is an enlarged sectional view of a main part of the power storage device shown in FIG. 1.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a plan view showing a power storage device according to one embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II of FIG. 1 and 2, the power storage device 1 of the present embodiment is used as a battery of various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle.

  The power storage device 1 may be a secondary battery such as a lithium ion secondary battery or a nickel hydride secondary battery, or may be an electric double layer capacitor. Further, power storage device 1 may be an all-solid-state battery. In the present embodiment, a case where the power storage device 1 is a lithium ion secondary battery will be described as an example.

  The power storage device 1 includes a laminate 2 and a laminate film 3 that is an exterior member that covers the laminate 2. In the present embodiment, the stacking direction (Z-axis direction) of the stacked body 2 is defined as a vertical direction.

  The laminate 2 has a structure in which the negative electrode 4 and the positive electrode 5 serving as electrodes, the negative electrode current collector 6, the positive electrode current collector 7, and the separator 8 are stacked. In the uppermost layer (one outermost layer) and the lowermost layer (the other outermost layer) of the laminate 2, the negative electrode current collectors 6 are arranged. The stacked body 2 includes a negative electrode 4, a negative electrode current collector 6, a negative electrode 4, a separator 8, a positive electrode 5, a positive electrode current collector 7, a positive electrode 5, a separator 8, and a negative electrode 4 arranged in this order in the stacking direction. The negative electrode 4, the positive electrode 5, the negative electrode current collector 6, the positive electrode current collector 7, and the separator 8 have, for example, a rectangular shape (a rectangular shape in a plan view) when viewed from the laminating direction.

  The negative electrode 4 is formed on both surfaces of the negative electrode current collector plate 6. Each negative electrode current collector plate 6 extends toward one side of the laminate 2 in the X-axis direction. The X-axis direction is a direction perpendicular to the laminating direction (Z-axis direction). Each negative electrode current collector plate 6 is bent inward in the stacking direction. And each negative electrode current collector plate 6 is electrically connected to each other.

  The positive electrode 5 is formed on both surfaces of the positive electrode current collector 7. Each positive electrode current collector 7 extends toward the other side of the laminate 2 in the X-axis direction. Each positive electrode current collector 7 other than the most centrally located positive electrode current collector 7 is bent inward in the stacking direction. The positive electrode current collectors 7 are electrically connected to each other.

  The negative electrode current collector 6 and the positive electrode current collector 7 are, for example, a pure metal foil or an alloy foil. Examples of the pure metal foil include a copper foil, an aluminum foil, a titanium foil and a nickel foil. Examples of the alloy foil include a stainless steel foil and an alloy foil of the pure metal.

  The negative electrode 4 includes a negative electrode active material and an electrolyte. The negative electrode active material is, for example, graphite, highly oriented graphite, mesocarbon microbeads, carbon such as hard carbon or soft carbon, lithium, an alkali metal such as sodium, a metal compound, and silicon, tin which can be alloyed with lithium. Or a compound thereof, or boron-added carbon. The electrolyte is, for example, a solid electrolyte, a solid polymer electrolyte or a gel electrolyte. Solid electrolytes include zirconia or beta alumina. The solid polymer electrolyte includes, for example, an alkylene oxide polymer compound such as polyethylene oxide (PEO) and polypropylene oxide (PPO), or a copolymer thereof. A gel electrolyte is an electrolyte that does not show fluidity completely or almost completely.

  The positive electrode 5 contains a positive electrode active material and an electrolyte. The positive electrode active material is, for example, a composite oxide, metallic lithium or sulfur. The composition of the composite oxide includes, for example, at least one of manganese, titanium, nickel, cobalt, and aluminum and lithium. The electrolyte is, for example, the same as the electrolyte of the negative electrode 4.

  The separator 8 is disposed between the negative electrode 4 and the positive electrode 5. The separator 8 is composed of the electrolyte contained in the negative electrode 4 and the positive electrode 5. Further, the separator 8 may be a porous film that can be filled with an electrolyte. When the separator 8 is made of a solid electrolyte, the separator 8 may have a substantially rectangular plate shape.

  A negative electrode tab 9 is electrically connected to each negative electrode current collector plate 6. A positive electrode tab 10 is electrically connected to each positive electrode current collector 7. The negative electrode tab 9 and the positive electrode tab 10 are formed of, for example, the same material as the negative electrode current collector 6 and the positive electrode current collector 7. The negative electrode tab 9 is taken out of the laminate film 3 on one side of the laminate film 3 in the X-axis direction. The positive electrode tab 10 is taken out of the laminate film 3 on the other side of the laminate film 3 in the X-axis direction.

  The laminate film 3 has an upper exterior part 11 (first exterior part) and a lower exterior part 12 (second exterior part) arranged to face each other in the stacking direction of the laminate 2. The upper exterior part 11 and the lower exterior part 12 have a substantially U-shape (hereinafter, substantially U-shaped in cross section) in a cross section cut perpendicular to the X-axis direction and the Y-axis direction. The Y-axis direction is a direction perpendicular to the X-axis direction and the Z-axis direction.

  The upper exterior portion 11 includes a top plate portion 13, a side plate portion 14 provided to bend with respect to the top plate portion 13, and projects outward from the tip of the side plate portion 14 in the X-axis direction and the Y-axis direction. Overhang 15. The lower exterior portion 12 has a bottom plate portion 16, a side plate portion 17 provided to be bent with respect to the bottom plate portion 16, and projects outward from the tip of the side plate portion 17 in the X-axis direction and the Y-axis direction. It comprises an overhang portion 18.

  The overhang portion 15 of the upper exterior portion 11 and the overhang portion 18 of the lower exterior portion 12 are joined to the negative electrode current collector 6, the positive electrode current collector 7, the negative electrode tab 9, and the positive electrode tab 10 by thermal welding. The overhang portions 15, 18 are also joined by heat welding.

  As shown in FIG. 3, the upper exterior part 11 and the lower exterior part 12 include a metal layer 20, an insulating resin layer 21 disposed outside the metal layer 20 in the stacking direction, and a metal layer 20. It has a three-layer structure composed of the sealing resin layer 22 disposed inside in the laminating direction. The metal layer 20 is formed of a pure metal or alloy such as aluminum, stainless steel, nickel or copper. The insulating resin layer 21 is formed of a resin such as polypropylene, polyethylene, or polyethylene terephthalate. The seal resin layer 22 is formed of a resin such as polypropylene or polyethylene.

  Between the inner wall surface 13a of the top plate portion 13 of the upper exterior portion 11 and the upper end surface 2a of the laminate 2 and between the inner wall surface 16a of the bottom plate portion 16 of the lower exterior portion 12 and the lower end surface 2b of the laminate 2 , Dummy layers 23 are respectively arranged. That is, the dummy layer 23 is disposed between the top plate portion 13 of the upper exterior portion 11 and the bottom plate portion 16 of the lower exterior portion 12 and the uppermost layer and the lowermost layer negative electrode 4 of the laminate 2, respectively. The inner wall surface 13a is a surface of the upper exterior part 11 that is perpendicular to the laminating direction. The inner wall surface 16a is a surface perpendicular to the laminating direction in the lower exterior part 12. The dummy layer 23 is in contact with the sealing resin layer 22.

  The dummy layer 23 is formed of, for example, a flat plate made of resin. The dummy layer 23 has a rectangular shape in plan view. The outer dimensions of the dummy layer 23 as viewed from the laminating direction are larger than the outer dimensions of the negative electrode 4 and the positive electrode 5 as viewed from the laminating direction. The external dimensions are dimensions in the X-axis direction and the Y-axis direction. Further, the thickness of the dummy layer 23 is larger than the thickness of the laminate film 3.

  The edge of the dummy layer 23 is located at the bent portion of the laminate film 3. That is, the edge of the upper dummy layer 23 is located at the boundary between the top plate portion 13 and the side plate portion 14 in the upper exterior portion 11. The edge of the lower dummy layer 23 is located at the boundary between the bottom plate portion 16 and the side plate portion 17 in the lower exterior portion 12. At this time, the edge of the dummy layer 23 is not bent inward in the stacking direction.

  As shown in FIG. 3, a chamfer 24 is provided at the edge of the main surface 23a of the dummy layer 23 on the laminate film 3 side. The chamfer 24 may have a flat shape or an R shape.

  Examples of the resin forming the dummy layer 23 include polypropylene, polyethylene, polyphenylene sulfide (PPS), and ethylene tetrafluoride / perfluoroalkoxyethylene copolymer resin (PFA).

  By the way, as the angle of the side plate portion 14 with respect to the top plate portion 13 in the upper exterior portion 11 of the laminate film 3 becomes closer to the vertical, the distance between the side plate portion 14 and the laminate 2 becomes shorter, so that the outer side of the upper exterior portion 11 flows. The laminate 2 is easily cooled by the air. However, as the angle of the side plate portion 14 with respect to the top plate portion 13 in the upper exterior portion 11 becomes closer to the vertical, when an external stress is applied to the power storage device 1, the edge of the negative electrode 4 located on the uppermost layer of the laminate 2 The part is easily affected by external stress, and the negative electrode 4 may be damaged. Similarly, as the angle of the side plate portion 17 with respect to the bottom plate portion 16 in the lower exterior portion 12 of the laminate film 3 becomes closer to the vertical, when an external stress is applied to the power storage device 1, The edge portion of the negative electrode 4 is likely to receive an external stress, and the negative electrode 4 may be damaged.

  In order to deal with such a problem, in the present embodiment, the inner wall 13a of the upper exterior unit 11 perpendicular to the lamination direction and the upper end surface 2a of the laminate 2 and the inner wall 13a of the lower exterior unit 12 perpendicular to the lamination direction are provided. Dummy layers 23 are respectively arranged between the wall surface 16a and the lower end surface 2b of the multilayer body 2, and the outer dimensions of the dummy layers 23 viewed from the laminating direction are the same as those of the negative electrode 4 and the positive electrode 5 viewed from the laminating direction. Larger than external dimensions. Therefore, when an external stress is applied to the power storage device 1, the external stress is applied to the dummy layer 23, so that the edge of the outermost layer of the negative electrode 4 in the stacked body 2 is less likely to receive the external stress. . This prevents the outermost negative electrode 4 in the laminate 2 from being damaged.

  Further, in the present embodiment, since the chamfer 24 is provided at the edge of the main surface 23 a of the dummy layer 23 on the laminate film 3 side, when the external stress is applied to the power storage device 1, the dummy layer 23 Of the laminate film 3 is less likely to bend inward in the laminating direction, and cracks are less likely to occur in the bent portion of the laminate film 3. Since the occurrence of cracks in the laminated film 3 is suppressed, the sealing performance with the outside is sufficiently ensured, so that air, moisture, foreign matter, or the like can be reliably prevented from entering the power storage device 1.

  In the present embodiment, since the thickness of the dummy layer 23 is larger than the thickness of the laminate film 3, the dummy layer 23 can sufficiently receive external stress.

  Note that the present invention is not limited to the above embodiment. For example, in the above embodiment, the thickness of the dummy layer 23 is larger than the thickness of the laminate film 3, but the present invention is not particularly limited to this, and the thickness of the dummy layer 23 may be equal to the thickness of the laminate film 3. Alternatively, the thickness of the dummy layer 23 may be smaller than the thickness of the laminate film 3.

  Further, in the above embodiment, the upper exterior part 11 and the lower exterior part 12 constituting the laminate film 3 each have a substantially U-shaped cross section. However, the present invention is not particularly limited to this. Only one of the upper and lower outer portions 12 may have a substantially U-shaped cross section, and the other of the upper and lower outer portions 11 and 12 may have a flat plate shape or a substantially flat plate shape. When only the upper exterior portion 11 has a substantially U-shaped cross section, the dummy layer 23 is disposed only between the inner wall surface 13a of the upper exterior portion 11 perpendicular to the laminating direction and the upper end surface 2a of the multilayer body 2. It should just be. When only the lower exterior part 12 has a substantially U-shaped cross section, the dummy layer 23 is provided only between the inner wall surface 16a of the lower exterior part 12 perpendicular to the laminating direction and the lower end face 2b of the multilayer body 2. It is sufficient if they are arranged.

  DESCRIPTION OF SYMBOLS 1 ... Power storage device, 2 ... laminated body, 2a ... upper end surface, 2b ... lower end surface, 3 ... laminated film (exterior member), 4 ... negative electrode (electrode), 5 ... positive electrode (electrode), 6 ... negative electrode current collector plate ( Current collector plate), 7: positive electrode current collector plate (current collector plate), 9: negative electrode tab (tab), 10: positive electrode tab (tab), 11: upper exterior part (first exterior part), 12: lower exterior part Part (second exterior part), 13a ... inner wall surface, 16a ... inner wall surface, 23 ... dummy layer, 23a ... main surface, 24 ... chamfer.

Claims (4)

A laminate in which the electrodes and the current collector are laminated,
An exterior member that covers the laminate,
A tab that is electrically connected to the current collector plate and that is taken out of the exterior member;
The exterior member has a first exterior portion and a second exterior portion that are arranged to face each other in a stacking direction of the laminate,
At least one of the first exterior part and the second exterior part has a substantially U-shaped cross section,
A dummy layer is arranged between an inner wall surface of at least one of the first exterior part and the second exterior part perpendicular to the lamination direction and an end face of the laminate in the lamination direction,
The power storage device, wherein an outer dimension of the dummy layer viewed from the stacking direction is larger than an outer dimension of the electrode viewed from the stacking direction. Each of the first exterior part and the second exterior part has a substantially U-shaped cross section,
2. The device according to claim 1, wherein the dummy layer is disposed between an inner wall surface of the first exterior portion and the second exterior portion perpendicular to the lamination direction and both end surfaces of the laminate in the lamination direction. 3. Power storage device.   The power storage device according to claim 1, wherein a chamfer is provided at an edge of the main surface of the dummy layer on the exterior member side.   The power storage device according to claim 1, wherein a thickness of the dummy layer is greater than a thickness of the exterior member.

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